The a-phase of the AI-Mn-Si ternary system has been precipitated from four liquid solutions (2.8wt% Mn-3.7wt% Si, 4.5wt% Mn-7wt% Si, 7.7wt% Mn-10wt% Si and 8.7wt% Mn-12.6 wt% Si) and equilibrated slightly over the melting point of the (secondary) solid solution. Quenching into water enabled the precipitates to be separated from the solid solution and the co-nodal tie-lines for the a-phase and liquid to be determined. The silicon content varied from 9.8 to 11.8wt%, while the manganese content, 29.6 ± 0.6wt%, did not vary significantly. The lattice parameter of the cubic unit cell decreased from 1.267 6(2) nm to 1.265 10(4) nm with increasing silicon. Neutron powder diffraction showed silicon to constitute approximately 50% of atoms on the icosahedral aluminium sublattices and 70% of a six-fold aluminium site in the interstices between the almost spherical, 54-atom clusters. This decrease in unit cell volume is interpreted as evidence for substitution of the silicon atoms on the six-fold sublattice.
Abstract-Microfluidic large-scale integration (mLSI) chips comprise hundreds or thousands of microvalves integrated into a chemically inert elastomeric substrate. The design of these chips is time-consuming, error-prone, and presently performed by hand. To enhance design automation, a routability-oriented placement algorithm based on simulated annealing is introduced. This paper investigates relevant issues including: (1) grid representation; (2) perturbation operations; (3) objective function; (4) uniform vs. heterogeneous component sizes; (5) spacing rules and their effect on routability; and (6) random vs. directed initial placement. Our results show how the above issues affect both the pre-routing estimate on the routability of the chips, the number of flow channel intersections (each of which requires the insertion of several microvalves), and total channel distance as reported by our router.
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